A random sample of 98 patients with common whiplash was examined early after trauma (mean +/- SD, 7.3 +/- 3.9 days) and again 6 months later. Cognitive functioning was assessed in conjunction with complaints, pain intensity, well-being, subjective cognitive impairment, neuroticism, and medication. At 6 months, 67 patients had fully recovered (asymptomatic group), while 31 were still symptomatic (symptomatic group). Symptomatic patients who were older at baseline, had a greater variety of symptoms, higher neck pain intensity, and greater subjective cognitive impairment. At baseline, both groups scored poorly on tests requiring complex attentional processing. All neuropsychological functions improved to normal at 6 months in both groups. This improvement cannot be explained by a practice effect, as shown by the results of normal volunteers. The symptomatic group showed delayed recovery regarding complex attentional functioning, which may be related to adverse effects of medication.